It is widely known in an automotive vehicle engine to transfer a portion of the engine output to a plurality of belt driven accessory components utilizing an endless serpentine belt. Typically, each component includes a pulley drivingly engaged with the belt and the belt is driven by an output pulley coupled directly to the crankshaft on the engine. The pulley of the component is rotatably mounted to a drive shaft. An example of such a belt driven accessory component is an alternator.
Internal combustion engines operate as a pulse system, constantly accelerating and decelerating and causing engine vibrations. As a result of these changing speeds, the belt driven accessory components, which are driven by the crankshaft, are continually trying to speed up and slow down. This can result in unacceptable levels of noise and vibration along with reduced component durability due to high fluctuating loads and vibrations. Additionally, rapid engine accelerations and decelerations, such as during transmission shifts and engine startup or shutdown, cause belt squeal from slippage between the belt and the pulley, as well as heavy impact loading on the belt.
It is known to provide a decoupler assembly operatively coupled between the pulley and the belt driven accessory component, such as the alternator, to allow the alternator drive shaft to “overrun” or rotate at a faster speed than the pulley and to allow the speed of the pulley to oscillate with respect to the alternator drive shaft due to oscillations in the engine speed. Examples of decouplers are disclosed in the U.S. Pat. No. 6,083,130, issued to Mevissen et al. on Jul. 4, 2000 and the U.S. Pat. No. 5,139,463, issued to Bytzek et al. on Aug. 18, 1992.
It is also known to provide a decoupler between the pulley and the belt driven accessory component to isolate vibrations therebetween reducing noise and impact loads. An example of such a decoupler is disclosed in U.S. Pat. No. 6,044,943, issued to Bytzek et al. on Apr. 4, 2000.
It remains desirable to provide a decoupler that is easier to manufacture and has better durability and functionality over conventional decoupler designs.